Well....
PW is hugely expensive. Very nice, but whether it's "worth" the extra money is all in the eyes of the beholder. In practical terms you'd be just as happy with a mid-range Shimano unit and simply replace when needed. It'll take years before you need to touch it.

While nice cranksets are always nice, I've used real budget parts on my commuter. They actually last longer due to the rings being steel, and I can get the whole set for the cost of one ring. Unless I'm trying to lighten the bike, it's a no-brainer.

Assuming you're friction shifting you can keep the DT shifters, but I'd forward a recommendation of not going above 8-speed at the back. Supposedly hitting the sweet spot gets kinda fiddly around there.
Again assuming you're friction shifting you can use pretty much any rear derailer. Supposedly there are some combos out there where cable pull gets so mismatched that you won't get the full travel, but it's really rare.

Wheels: Looking at the pic it seems possible that you have a freewheel rear while todays standard is the freehub design - which may also require another dropout width. But don't worry, steel frames can be cold set. You can stay with freewheel if you insist, but finding a touring-rated freewheel rear may be tricky. It also plays in on parts accessibility. Freehubs you can get serviced and parts to just about anywhere, while nice freewheels are almost always an item that has to be ordered.